how to do check column values is not clash if all value correspond to same value of other column, if-CodePudding

s_id    PSC
pbx     4
pbx     5
pbx     7
pby     8
pbn     8
pby     7
pbn     8

now check PSC of pbx does not clash bt PSC of pbn clashed

CodePudding user response：

If clashed means there are unique values per groups by s_id use:

df['new'] = np.where(df.groupby('s_id')['PSC'].transform('nunique').ne(1), 
                     'not clash',
                     'clashed')

print (df)
  s_id  PSC        new
0  pbx    4  not clash
1  pbx    5  not clash
2  pbx    7  not clash
3  pby    8  not clash
4  pbn    8    clashed
5  pby    7  not clash
6  pbn    8    clashed

CodePudding user response：

clashed if all values in s_id groups are the same (duplicated):

df['clash'] = df.duplicated(['s_id', 'PSC'])\
                .groupby(df['s_id'])\
                .transform('all')\
                .map({True: 'clashed', False: 'not clashed'})
print(df)

  s_id  PSC        clash
0  pbx    4  not clashed
1  pbx    5  not clashed
2  pbx    7  not clashed
3  pby    8  not clashed
4  pbn    8      clashed
5  pby    7  not clashed
6  pbn    8      clashed